1. Field of the Invention
The present invention relates to a flip-chip type semiconductor device, a process for manufacturing such a flip-chip type semiconductor device, and a process for mounting such a flip-chip type semiconductor device on a wiring-board.
2. Description of the Related Art
A flip-chip (FC) type semiconductor device has been developed to meet the demands of higher performance, is smaller and lighter size, and higher speed for a piece of electronic equipment. Generally, the FC type semiconductor device has a plurality of electrode pads arranged on a semiconductor chip (i.e. bare chip), and a plurality of metal bumps bonded to the electrode pads. Each of the metal bumps may be formed of solder or gold, and serves as an electrode terminal or lead.
The FC type semiconductor device is frequently assembled in a BGA (ball grid array) type package, which includes a wiring-board, usually called a package board or interposer. The wiring-board has a plurality of electrode pads arranged on a lower or bottom surface thereof, and a plurality of solder balls bonded to the electrode pads, with the solder balls forming the ball grid array (BGA).
In the BGA type package, the FC type semiconductor device is mounted on an upper or top surface of the wiring-board, such that the respective metal bumps of the FC type semiconductor device are correspondingly contacted with and bonded to electrode pads formed and arranged on the upper surface of the wiring-board.
In particular, there is a mirror image relationship between the arrangement of electrode pads of the FC type semiconductor device and the arrangement of electrode pads of the wiring-board. Thus, when the FC type semiconductor device is flipped over and put in place on the upper surface of the wiring-board, the respective electrode pads of the FC type semiconductor device are electrically connected to the electrode pads of the wiring-board through the intermediary of the metal bumps. Then, the respective metal bumps of the FC type semiconductor device are securely bonded to the electrode pads on the wiring-board by either an ultrasonic-pressure bonding method or a heat-pressure bonding method.
After the metal bumps are bonded to the electrode pads, a resin-underfilling process is performed such that the space between the FC type semiconductor device and the wiring-board is filled with a suitable resin, to thereby seal the arrangement of metal bumps, resulting in production of the BGA type package.
On the other hand, the FC type semiconductor device may be directly mounted on a motherboard for a piece of electronic equipment, such that the respective metal bumps of the FC type semiconductor device are contacted with and bonded to electrode pads formed and arranged on the motherboard. Similarly, after the metal bumps are bonded to the electrode pads, the resin-underfilling process is performed such that the space between the FC type semiconductor device and the motherboard is filled with a suitable resin to seal the arrangement of metal bumps.
In either case, it is troublesome to perform the resin-underfilling process, because the space between the FC type semiconductor device and the wiring-board or motherboard is very narrow. Namely, it is hard to introduce the resin into the narrow space between the FC type semiconductor device and the wiring-board or motherboard.
Conventionally, in order to omit the troublesome resin-underfilling process, it has been proposed that an adhesive resin layer is previously provided on either the FC type semiconductor device or the wiring-board before the FC type semiconductor device is mounted on the wiring-board, as shown in, for example, Japanese Laid-Open Patent Publications (KOKAI) No. HEI-09-097815, No. HEI-11-274241, No. HEI-11-297750, No. 2000-286302, No. 2001-127395, No. 2001-237274, and No. 2001-308140.
Frequently, each of the metal bumps is formed as a sprout-shaped bump. In this case, when the adhesive resin layer is formed on the surface of the FC type semiconductor device on which the sprout-shaped bumps are arranged and bonded, tip ends of the sprout-shaped bumps are protruded from a surface of the adhesive resin layer so as to be exposed to the exterior.
Then, the FC type semiconductor device is flipped over and put in place on the wiring-board or motherboard, the respective electrode pads of the FC type semiconductor device are electrically connected to the electrode pads of the wiring-board through the intermediary of the sprout-shaped bumps, with the adhesive resin layer being intervened between the FC type semiconductor device and the wiring-board. Subsequently, the respective sprout-shaped bumps are securely bonded to the electrode pads of the wiring-board by either the ultrasonic-pressure bonding method or the heat-pressure bonding method. When the bonding of the sprout-shaped bumps to the electrode pads is completed, the adhesive resin layer is adhered to the wiring-board or motherboard, and thus the arrangement of sprout-shaped bumps is sealed by the adhesive resin layer.
Nevertheless, it is hard to handle the FC type semiconductor device with the adhesive resin layer, because the exposed tip ends of the sprout-shaped bumps are very susceptible to damage and injury, resulting in a lowering of production efficiency of FC type semiconductor devices. Also, the adhesive resin layer is liable to be deteriorated for the reasons involved in a process for the formation of the adhesive resin layer, as stated hereinafter.